- Synthesis of 2-Substituted 1,2,3-Triazoles via an Intramolecular N–N Bond Formation
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An efficient synthesis of 2-aryl 1,2,3-triazoles based on an intramolecular N–N bond formation is described. Selective activation of bis-hydrazone at the dimethylamino hydrazone group with MeI forms a mono-hydrazonium species. Treatment of the hydrazonium
- Chen, Cheng-yi,Lu, Xiaowei,Holland, Mareike C.,Lv, Shichang,Ji, Xuebao,Liu, Wei,Liu, Jie,Depre, Dominique,Westerduin, Pieter
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supporting information
p. 548 - 551
(2019/12/24)
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- Flash vacuum pyrolysis of 1,2,5-oxadiazole 2-oxides and 1,2,3-triazole 1-oxides
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The flash vacuum pyrolysis (FVP, 450-600 °C/10-3 mmHg) of 3,4-diaryl- and 3,4-dialkyl-1,2,5-oxadiazole 2-oxides (furoxans) has been investigated. In all cases the 1,2,5-oxadiazole ring cleaved cleanly at O(1)-N(2) and C(3)-C(4) to afford two nitrile oxide fragments, which were trapped in high yield (75-97%) as their isoxazoline cycloadducts by reaction with alk-1-enes. At higher temperatures (700-800 °C) isocyanates were formed as by-products. The dimerisation of acetonitrile oxide to dimethylfuroxan was followed by 1H NMR spectroscopy, and the rate constant for the 2 nd order reaction determined. The furoxans were converted into isocyanates in good yield (61-95%) by FVP, followed by sulfur dioxide-mediated isomerisation of the resulting nitrile oxides. 2,4,5-Trisubstituted-1,2,3- triazole 1-oxides showed greater thermal stability, but at 700-800 °C decomposition of the 4,5-dimethyl compound 25b lead to 1,2-di(5-methyl-2-phenyl- 1,2,3-triazol-2-yl)ethane as the major product; attempts to trap acetonitrile oxide were unsuccessful. ARKAT USA, Inc.
- Mitchell, William R.,Paton, R. Michael
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experimental part
p. 34 - 54
(2011/02/21)
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- Reaction of 2-phenyl substituted 1,2,3-triazol 1-oxides with acylating agents. Preparation of hydroxy- halogen- hydroxymethyl- and chloromethyltriazoles
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2-Phenyltriazol 1-oxides react with acetyl chloride producing acetoxy- and chloro-substituted triazoles.The substituents enter the 5 and the 4-position.When these are not accessible the substituents go to lateral positions and to the phenyl group producing acetoxymethyltriazoles and 2-halogenophenyl triazoles.Acetic anhydride reacts reluctantly while trifluoroacetic anhydride is more reactive producing trifluoroacetoxytriazoles.The reactions provide effective routes to hydroxy- and hydroxymethyltriazoles.Several mechanisms among which a cyclic one are operating.
- Begtrup, Mikael
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p. 717 - 728
(2007/10/03)
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- 1,2,3-Triazol-1-imines. 1. The Synthesis and Lead Tetraacetate Oxidation of Biacetyl Benzoylhydrazone Arylhydrazones to the Novel 2-Aryl-N-benzoyl-4,5-dimethyl-1,2,3-triazol-1-imines
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The synthesis and the Pb(OAc)4 oxidation of the mixed bishydrazones of biacetyl 7 was studied.The formation of the novel N-benzoyl-1,2,3-triazol-1-imines 9 from the oxidation of 7 provided support to the proposed in the past mechanism for the oxidation of bis-aroylhydrazones of α-dicarbonyl compounds 4.Thermolysis and photolysis of 9a in DMSO was carried out.The results suggested that benzoylnitrene was formed in the photochemical reaction, and therefore compounds such as 9 could serve as non-azide aroyl nitrene precursors.For 9a the results of the X-ray analysis were correlated with charge densities and bond orders gleaned by the MNDO method.Product 9d was alternatively synthesized by the addition of photochemically generated bezoylnitrene to the 1,2,3-triazole 21.
- Hadjiantoniou-Maroulis, C. P.,Maroulis, A. J.,Terzis, A.,Mentzafos, D.
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p. 2252 - 2257
(2007/10/02)
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- Activation of Exocyclic α-Positions of Azole N-Oxides by O-Silylation
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Exocyclic α-positions at immonium ring carbon atoms of pyrazole and 1,2,3-triazole 1-oxides are selectively attacked in a one-pot sequence comprising silylation with iodotrimethylsilane, deprotonation with 1,2,2,6,6-pentamethylpiperidine and allylic substitution of the trimethylsilyloxy group with the iodide ions liberated by the silylation.In this way 3- and 5-iodomethylpyrazoles as well as 4-iodomethyl-1,2,3-triazoles are obtained in good yields.These may be useful for the preparation of heteroarylmethyl derivatives since the iodine atom can be displaced by even weak nucleophiles such as acetate ions.The side chain iodination is complementary to O-alkylation of the N-oxides followed by nucleophilic attack which preferentially takes place at ring carbon atoms.
- Begtrup, Mikael,Vedso, Per
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p. 2555 - 2564
(2007/10/02)
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